Tenter unit

ABSTRACT

A width stretching unit for textile webs includes a first needle disc unit having first and second needle discs disposed along a first axis at a distance corresponding to the width of the web of material and a second needle disc unit having a second axis which is situated in the pivoting plane parallel to the first axis, and having third and forth needle discs arranged perpendicular to the second axis that rotate about the second axis with the same peripheral speed as the first and second needle discs. The axial distance between the third and fourth needle discs is equal to the axial distance between the first and second needle discs in a zone of increased distance between the first and second needle discs. The edges of the first and third needle discs and the edges of the second and fourth needle discs practically touch one another in the zone of increased-distance so that it is possible for the web of material to be transferred from the first and second needle discs to the third and fourth needle discs, respectively, without relinquishing the attachment of the web to the needles on at least one of the first or third needle discs and at least one of the second or fourth needle discs.

FIELD OF THE INVENTION

The invention relates to a device for stretching the width of a web ofmaterial and more particularly to a width stretching unit having axiallyspaced needle discs, each of which rotates about an axis that pivots toprovide a zone of reduced width between the needle discs and a zone ofincreased width between the needle discs.

BACKGROUND OF THE INVENTION

The term "needle discs" denotes discs similar to wheels which rotatewith the web of material, usually consisting of metal, with theirperipheral edges being provided all round with closely set needles ofidentical lengths. The needle points extend radially outward andpenetrate the edges of the web of material to tension the same or keepit tensioned in the direction of the width.

A width stretching unit of this type is known from DE-PS 480 155. A webof material runs onto two obliquely disposed needle discs in the zonewhere the needle discs have a reduced axial distance between them attheir needle edge. The web passes around the needle discs throughapproximately 240°, the edges of the needle discs moving axially apartso that the web of material engaged by the needles at the selvedges isstretched width-wise. The web leaves the needle discs in a plane offsetby an angle of about 90° to the entry plane. The needle discs areadjustable in respect of their angular position and transverse distanceand are driven jointly.

DE 41 41 779 Al discloses an apparatus for levelling a web of material,such apparatus also operating with two needle discs, the angularposition of which is variable. The purpose of this apparatus is to levela web of material with much less expense than a conventional tenteringframe and yet achieve a treatment equivalent to the levelling of atentering frame.

A common feature of the known devices having relatively pivotable needlediscs disposed on a common axis is that the treated web of material isreleased after it leaves the needle discs. If such apparatus is used inmercerizing and similar plants, the web of material tends to shrinkagain after width stretching. After leaving the needle discs itimmediately contracts in the transverse direction.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the invention is to develop a width stretching unit inwhich the width stretching effect achieved is maintained positively overa certain travel of the web of material. The width stretching unit is ofthe type having a first needle disc unit having first and second needlediscs disposed along a first axis at an axial distance corresponding toa width of the web of material, the first and second needle discs havinga multiplicity of peripherally distributed needles pointing radiallyoutward. The multiplicity of needles are intended for insertion intoselvedges of the web of material. The stretching unit also includes apivoting mechanism for pivoting a first rotational axis and a secondrotational axis of the first and second needle discs, respectively, in apivoting plane passing through the first axis. The stretching unitfurther includes a pinning mechanism for pinning the web of material byits edges onto the multiplicity of needles of the first and secondneedle discs in a region of reduced axial distance between edges of thefirst and second needle discs.

Maintaining the width stretching effect over a certain travel of the webof material is achieved by the present invention which includes a secondneedle disc unit associated with the first needle disc unit, the secondneedle disc unit having a second axis parallel to the first axis andsituated in the pivoting plane, the second needle disc further havingthird and fourth needle discs rotatably mounted substantiallyperpendicular to the second axis, the third and fourth needle discsrotating about the second axis at the same peripheral speed as the firstand second needle discs, an axial distance between the third and fourthneedle discs being equal to the axial distance between the first andsecond needle discs in a zone of increased distance between the firstand second needle discs, wherein the edge of the first needle discpractically touches the edge of the third needle disc in the zone ofincreased distance, and the edge of the second needle disc practicallytouches the edge of the fourth needle disc in the zone of increaseddistance, so that it is possible for the web of material to betransferred from the first and second needle discs to the third andfourth needle discs, respectively, without relinquishing the pinning onat least one of the first or third needle discs and at least one of thesecond or fourth needle discs.

Thus, a first needle disc unit has associated therewith a second needledisc unit. The web of material passes from the first needle disc unit tothe second needle disc unit at the location on the first needle discunit of increased width stretching. The web of material is not releasedduring the transfer from the first needle disc unit to the second needledisc unit, and is held fast on the needles in transverse tension over acertain peripheral travel of the second needle disc unit.

One particular application of a width stretching unit of this kind is amercerizing plant in which the width stretching unit follows thediffusion zone which follows the application of the mercerizing liquor.In this zone the web of material has a strong tendency to shrinktransversely and longitudinally and is prevented from so doing by thesecond needle disc unit.

A palmering disc arrangement, in which the web of material runs overinclined discs at its selvedges and is transversely retained thereon sothat it must participate in the increase in the distance as the discsrotate, is the subject matter of DE-PS 610 937. There, the web ofmaterial passes to a directly following unit in the form of a calenderroller, on which it is held flat in a fixed fabric guide system.However, the transfer is not effected without relinquishing the fixedfabric guide system nor in such manner that the web of material issubsequently engaged only at the edge and held in the transversedirection.

According to the present invention, the degree of width stretching isadjusted by pivoting the two needle discs of the first needle disc unit.

In order automatically to adjust the distance between the needle discsof the second needle disc unit to the new width position, the mounts ofthe needle discs of the second needle disc unit may be joined to themounts of the respective needle discs of the first needle disc unit.Thus, when the first needle disc unit is adjusted, the second needledisc unit is thereby simultaneously and automatically adjusted as well.

One advantageous construction and arrangement includes a pivoting drive.The pivoting drive may be a linear actuator mounted axially outside of apivoting element to which the first and second needle discs are mounted.The linear drive may be mounted such that the linear motion of the drivepivots the pivoting element about a pivot axis, to thereby change therelative planes of rotation of the first and second needle discs.

An important feature is the support drum that may be provided betweenthe needle discs of first needle disc unit and/or between the needlediscs of the second needle disc unit. The support drum may substantiallyfill the axial gap between the needle discs and may have a diametersubstantially equal to the diameter of the needle discs. A web ofmaterial deflected into a partly cylindrical shape by needle discsengaging the selvedge and subject to transverse tension tends tocontract radially, i.e., extend concavely between the needle discs. Thiscan be counteracted by the support drums, which prevent contraction.

Advantageously, the support drum can be adjustable between the needlediscs with respect to its length, i.e., the support drum is adjustablein a direction transverse to the web of material, such that the supportdrum may adjust to the position to which the needle discs have been set.This can be achieved particularly by the construction wherein thesupport drum may consist of two inter-engaging parts, although it caninclude more than two appropriately constructed axially inter-engagingparts. For example, the support drum may include at least two coaxialcylindrical parts of the same diameter, the periphery of which consistsof freely projecting finger-like segments that have gaps spacedperipherally. The coaxial parts may thus engage one another withcorresponding finger-like segments engaging the gaps on the opposingcoaxial part. The two parts may further be axially adjusted to therebyadjust the length of the support drum.

One arrangement of the two needle disc units is a superposed arrangementhaving the first needle disc unit disposed above the second needle discunit with the web of material being guided onto the top apex of thefirst needle disc unit. This has a number of advantages. For example, itpermits placement of an operator's station positioned to allowobservation of the entry of the web of material onto the first needledisc unit. It is also optionally possible to apply a treatment liquid,during and after width stretching, to the web of material extendingaround the needle disc units, so that the web can be provided with thetreatment liquid in its width-stretched position. For example, in thecase of mercerization, washing of the mercerizing liquor can be startedon the needle disc units, with the result that the web of material losesits tendency to shrink before being released. In this way, the importantfirst phase of stabilization of the web of material to which the liquorhas been applied can take place without any risk of loss of width owingto the web of material being prematurely released. Of course thesuperposition is also advantageous in terms of reduced floor arearequirements.

Before the web of material runs onto the first needle disc unit, it maybe advantageous to provide selvedge straighteners at both edges toensure that the web of material passes to the needles in a desirablewidth position.

Placement of re-needling systems at the selvedges just subsequent to thepoint of transfer of the web from the first needle disc unit to thesecond needle disc unit is important in practice. If no special stepsare taken, only the longitudinal tension in the web of material isavailable at the transition from the first needle disc unit to thesecond needle disc unit to engage the web selvedges on the needles ofthe second needle disc unit as it runs onto the same. Since there-needling takes place at a point where there may be considerabletransverse tension in the web of material, the engagement of the web ofmaterial onto the needles of the second needle disc unit must beeffected even under difficult conditions.

To assist this operation and make it more reliable, a re-needling systemwhich presses the edges of the web of material radially from the outsideinto the needles of the second needle disc unit may be provided.

In one possible embodiment, a re-needling system may include a rollerwhich is provided with peripheral grooves for the passage of the needlesand which rolls on the edge of the material or the periphery of theassociated needle discs and which presses the web of material down ontothe edge of the needle discs next to the needles.

The roller, however, is only one possible construction of a re-needlingsystem of this kind. Revolving brushes, suitably shaped pressure rails,or a nozzle system directing air or a liquid medium radially fromoutside onto the edge of the web of material in the region of theneedles may be used in order to press the edge of the web onto theneedles.

According to one embodiment of the invention, the associated roller maybe mounted on the support element which also serves to support the firstneedle disc unit. The purpose of this is that the roller willautomatically move during a width adjustment and will always retain itscorrect position relative to the edge of the needle disc.

In order further to secure this position, the roller may have a radiallyprojecting collar by which the roller is pressed resiliently and axiallyfrom outside against the edge of the associated needle disc. In this waythe roller is always exactly positioned relative to the edge of theneedle disc so that the needles always run cleanly through theperipheral grooves of the roller.

Another aspect of the present invention relates to the web of materialrunning onto the first needle disc unit from the last guide roller incases in which the latter is situated with its top apex at substantiallythe same height as the top apex of the first needle disc unit and inwhich the web of material is guided in a fixed system as far as the lastguide roller. Typically, on the transition from the last guide roller tothe first needle disc unit, there is, due to the geometry, a free fabricsection which may be very undesirable.

The construction according to a further embodiment of the inventionincludes a deflecting roller disposed between the last guide roller andthe first needle disc unit. The embodiment is intended to obviate thefree fabric section by completely maintaining the fixed web guidancesystem until the web runs onto the first needle disc unit. In order touniformly introduce the deflecting roller into the nip between the lastguide roller and the first needle disc unit, a certain flexibility ofthe mounting of the deflecting roller is preferred.

In a further embodiment of the present invention, a fixed web guidancesystem is maintained as far as possible without any gaps, at the pointwhere the web leaves the second needle disc unit. This may be achievedby a de-needling roller. The de-needling roller takes the web ofmaterial tangentially off the second needle disc unit. Due to the weightof the de-needling roller and the web tension, the de-needling rollerbears on the first follower roller, the de-needling roller being freelyvertically movable in a guide. The de-needling roller is positioned suchthat its periphery bears on the follower roller and is just beyond thereach of the needles of the second needle disc unit.

The guidance system may be adjustable horizontally, i.e., towards oraway from the second needle disc unit, to thereby permit optimization ofthe position of the de-needling roller relative to the second needledisc unit.

According to a further aspect of the width stretching unit according toa possible embodiment of the invention, the width stretching of the webof material can be automated by connecting the pivoting drives for thefirst needle disc unit, which experience the web transverse tension, byusing, for example, force sensors. Signals from the force sensors may beinput to a control system which, by way of a drive en motor, controlsthe width adjustment of the second needle disc unit and hence also ofthe first needle disc unit.

A measuring device may be provided to measure the actual value of theset width of the second needle disc unit. The signal therefrom may beinput to the control system.

A closed-loop control system can be associated with the open-loopcontrol system to control the width setting of the second needle discunit in such manner that the transverse tension of the web of materialremains between a minimum and a maximum value, i.e., in a set range.

The web of material must not become limp in the transverse direction ifthe width stretching unit is to operate effectively. On the other hand,it should not be so strongly stretched transversely as to cause damage,particularly at the web selvedges. The maximum tension tolerated by aspecific web of material is known from experiments. Thus, the control issuch that as the web passes through the width stretching unit, the webis subjected to a predetermined transverse tension and in this wayundergoes a constant structural change.

In order to avoid the second needle disc unit elements moving apart tothe maximum width in the event of an unforeseen tearing or de-needlingof the web selvedges, the control may be carried out to preventuncontrolled width-wise movement of the second needle disc unit.

In order to counteract any longitudinal shrinkage such as occursparticularly in the case of mercerization, as well as to influence theweb elongation in the transverse direction, it may be advantageous tocombine the width stretching unit with a longitudinal stretching zone.In the case of a width-stretching unit having superposed needle discunits, the longitudinal stretching zone may advantageously precede thewidth stretching unit because then the longitudinal stretching zone mayform the transition zone required to pass from the height of theupstream part of the plant to the apex height of the top needle discunit.

All the features described may be used both individually and in anydesired combination.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplified embodiments of the invention are illustrated in the drawingswherein:

FIG. 1 is a diagrammatic side elevation of a width stretching unitincorporated in a continuous treatment plant.

FIG. 2 is a diagrammatic elevation in the direction of arrows II--II ofFIG. 1, with the operator's station omitted.

FIG. 3 is a perspective elevation of the mutual engagement of theneedles of cooperating needle discs.

FIG. 4 is a side elevation of the width stretching unit.

FIG. 5 is a perspective detail elevation of the zone in which the webruns onto the needle disc units.

FIG. 6 is a perspective side elevation of the width stretching unit fromthe opposite side with respect to FIG. 4.

FIG. 7 is an enlarged detail of FIG. 1 with a re-needling system.

FIG. 8 shows the re-needling system according to FIG. 7 from above.

FIG. 9 is a longitudinal section through the roller of the re-needlingsystem to an enlarged scale.

FIG. 10 is a partial elevation, corresponding to FIG. 1, of anembodiment which is modified at the width stretching unit inlet andoutlet.

FIG. 11 is an elevation, corresponding to FIG. 2, of an embodiment withautomation elements.

DETAILED DESCRIPTION OF THE DRAWINGS

The width-stretching unit having the general reference 100 in FIG. 1 ispart of a mercerizing plant in the exemplified embodiment illustrated.The mercerizing plant comprises an upstream part in the form of adiffusion section 1, through which the web of material 4 passes afterthe mercerizing liquor has been applied. In the diffusion section 1 themercerizing liquor has the opportunity of completely diffusing into theweb of material 4.

All the rollers and needle discs referred to have parallel axesextending in the direction of the width of the material web 4.

Following the diffusion section 1 is a longitudinal stretching zone 2,in which the material web 4 is transferred from the height of thediffusion section 1, i.e., about half man height, to a greater height ofabout 2 meters in a fixed material guidance system. The longitudinalstretching zone 2 comprises fixed guide rollers 7, guide rollers 8 and8" mounted in tension sensors 8', floating guide rollers 9, and a driventraction roller 10. By way of the drive for the latter it is possible tostretch the material web 4 longitudinally before the width stretchingoperation and to control the longitudinal tension occurring in theseconditions in the web 4 by means of the preceding roller 8 with thetension sensors 8'. The two guide rollers 8, 8" do not bear againsttheir neighboring rollers, but can shift slightly under the pull of theweb 4 to permit measurement in the tension sensors 8'. The sequence ofthe rollers 8, 7, 9, 7, 9, 9, 10, 8" making up the longitudinalstretching zone 2 extends upwards, i.e., the subsequent rollers of thesequence have their axes at an increasingly higher level so that adifference in height can be overcome.

From the top guide roller 8" as the last roller in the sequence the webof material 4 extends substantially horizontally from the longitudinalstretching zone 2 into the width stretching unit 100. This comprises afirst needle disc unit 20, which is at the top in the exemplifiedembodiment, and a second needle disc unit 40 disposed verticallytherebeneath. The web of material 4 runs onto the top needle disc unit20 in the region of its top apex, extends around the top needle discunit 20 through about 180°, and is transferred at point 3 to the bottomneedle disc unit 40. The web 4 passes around the bottom needle disc unit40 through about 270° and leaves the bottom needle disc unit 40 at point14. The web 4 is taken out of the needles 30 by a guide roller 21 and istransferred by another guide roller 23 to the following or downstreampart of the machine, which in this exemplified embodiment is thestabilizing section 22 of the mercerizing machine.

An operator's station 24 extending across the width of the web ofmaterial is disposed above the substantially horizontal guide zoneformed by the guide rollers 21, 23. From the operator's station 24, anoperator 25 can follow the correct entry of the web 4 onto the firstneedle disc unit 20.

In order to ensure reliable attachment of the edges of the web 4 ontothe first needle disc unit 20, a mechanical selvedge straightener 5 isprovided on each side of the first needle disc unit 20 immediatelybefore the point of entry of the web, and biasing brush rollers 6 areprovided above the two needle discs of the first needle disc unit 20 topress the edges of the web of material into the needles 30 of the firstneedle disc unit 20. The presence of the selvedge in the region of theselvedge straightener 5 is detected by an electronic selvedge detector12, and correct pinning of the material, i.e., the presence of theselvedge in the region of the needle discs, is detected by correspondingsensors 18.

The actual width stretching of the fabric is effected by the firstneedle disc unit 20, while the bottom needle disc unit 40 maintains thewidth of the fabric during its travel over the 270°. In this exemplifiedembodiment, an application system for treatment liquid in the form of apair of spray tubes 16 is disposed beneath the bottom needle disc unit40. The spray tubes 16 spray water or highly diluted liquor radiallyfrom outside against the web 4 in order to initiate stabilization atthis stage. Surplus treatment liquid is discharged via a trough 17disposed beneath the bottom needle disc unit 40.

FIG. 2 shows the construction of the two needle disc units 20 and 40 ingreater detail.

The first needle disc unit 20 in the direction of travel of the web 4,i.e. the top unit 20 in this exemplified embodiment, comprises twoneedle discs 26, 28 of a diameter of about 800 mm. The two needle discs26, 28 are disposed in the region of the selvedges 4' of a web of amaterial 4 along and substantially perpendicular to a first axis 27. Thediscs 26, 28 have at their periphery closely set radial needles 30 whichproject freely radially about 10 to 15 mm. In use, the radial needles 30penetrate the selvedges 4' of the web of material 4 and hold the samefast axially. The needle discs 26, 28 are mounted for rotation aboutaxes 35, 37 on journals 32, 34 directed substantially towards oneanother. The journals 32, 34 are secured at the respective top ends ofsubstantially upright pivoting elements 36,38. The upright pivotingelements 36,38 are pivotable about pivot axes 15 which are perpendicularto the plane passing through the axis 27 of the top needle disc unit 20and the axis 47 of the bottom needle disc unit 40 and which extendtangentially to the needle discs 26, 28. Thus, on a pivoting movement ofthe associated pivoting elements 36,38, the edges of the needle discs26, 28 at their bottom apices remain in the region of the pivot axes 15.Also, on a pivoting movement of the pivoting elements 36, 38, the axesof rotation 35, 37 of the two needle discs 26, 28 shift as indicatedfrom a position of alignment to an oblique position as shown in FIG. 2.The pivoting movement is produced by pivoting drives 13 each constructedas a linear drive, e.g., as a spindle or as a piston and cylinder unit.Each pivoting drive 13 engages a point of engagement 31 on the outsideof the pivoting elements 36, 38 in the region of the axes 35, 37 at oneend. At the other end, the pivoting drive 13 engages a point ofengagement 31' on substantially upright support elements 56, 58.

The pivot axis 15 is formed by a bearing at the pair of substantiallyupright support elements 56, 58 associated with the bottom needle discunit 40. In the elevation shown in FIG. 2, the support elements 56, 58are substantially T-shaped and have cross-bars 56', 58', respectively,which are substantially parallel to the axis 47 of the bottom needledisc unit 40. At the inner free ends of the cross-bars 56', 58' aredisposed the bearings with the pivot axes 15. At the outer free ends aredisposed the other point of engagement 31' for the associated pivotingdrive 13. Thus, on each side of the top needle disc unit 20, thepivoting drive 13 is disposed outside the pivoting element 36, 38 and isable to pivot the same in the direction of the arrow, so that theinclination of the needle discs 26, 28 is variable. The support elements56, 58 have webs 56", 5" disposed substantially perpendicular to thecross-bars 56', 58'. The webs 56", 58" are, at the bottom, each weldedto a hub 42, 44 respectively disposed on a shaft 41 having the axis 47.The shaft 41 is mounted in brackets 43 in the machine frame.

On the inside of the hubs 42, 44, the two bottom needle discs 46, 48 ofthe second needle disc unit 40 are mounted rotatably on the shaft 41 andhave a diameter of about 1000 mm in the exemplified embodiment. They areso positioned in the axial direction that each outer edge with theneedles 30 is situated in the same transverse plane of the axis 47 asthe respective pivot axis 15. In the region of the pivot axis 15 theperipheries of the needle discs 26 and 46, 28 and 48, respectively, aresituated directly opposite one another with a slight spacing 55. Thespacing 55 is only slightly in excess of the length of the needles 30.The situation does not change when the needle discs 26, 28 are changedin respect of their inclination.

The hubs 42, 44 and with them the needle discs 46, 48 are displaceablealong the shaft 41 in the direction of the arrows 77 for adjustment ofthe axial position of the needle discs 46, 48 to the web width. In theevent of such displacement, the support elements 56, 58 and 36, 38 arealso entrained and shift jointly with the same. Thus the mutual positionof the needle discs 26 and 46, 28 and 48 is maintained in the region ofthe pivot axes 15 even in the event of displacement of the needle discs46, 48.

The pivoting element 36 and the support element 56, on the one hand, andthe pivoting element 38 and the support element 58, on the other hand,respectively form a support 50 which constitutes a self-containedassembly, is adjustable in the axial direction, carries both needlediscs of one side, and, in the event of an adjustment, entrains the twoneedle discs jointly while maintaining their same axial position ortheir direct opposite position in the region of the pivot axis.

When the web of material 4 runs onto the top of the first needle discunit 20 and passes round the same through 180° in the downward directionwith reference to FIG. 2, it is stretched in the direction of the widthbecause the needles 30 engaging the selvedges 4' of the web of material4 move axially away from one another. A flexible fabric, such as atextile web, has the tendency to constrict under such transverse tensionduring a partly cylindrical path, so that the "diameter" at the centerbecomes less than at the edges. To obviate this phenomenon, the twoneedle disc units 20, 40 comprise support drums 29, 49 between the topneedle discs 26, 28, and the bottom needle discs 46, 48, respectively.The support drums 29, 49 rotate with their respective needle discs 26,28; 46, 48. In the exemplified embodiment, the support drums 29, 49 eachconsist of two identical cylindrical halves 29', 29"; 49', 49", thediameter of which is equal to the diameter of the respectivelyassociated needle discs 26, 28; 46, 48. The halves 29', 29" and 49', 49"are disposed coaxially on the axes 27, 47 respectively and rotate withthe needle discs 26, 28; 46, 48. At the facing sides, the halves 29',29" are divided up into peripherally uniformly distributed axis-parallelnarrow finger-like segments 51, between which are axis-parallel recesses52 of a width somewhat in excess of the width of the segments 51. Thus,the facing ends of the segments 29', 29" can be pushed axially insideone another and also shifted axially relative to one another as shown inFIG. 2, without the support of the web of material unduly suffering as aresult in the middle zone. On an axial displacement of the supports 50in the direction of the arrow 77, the halves 29', 29"; 49', 49" areentrained so that the length of the support drums 29, 49 whichsubstantially fill the gap between the needle discs 26, 28; 46, 48, inthe axial direction, is automatically adjusted.

FIG. 3 shows in detail the engagement zone of the associated needlediscs by reference to the example of the needle discs 26, 46. The needlediscs 26, 46 have axially projecting collars 53, 54 at the edges. Thecollars 53, 54 are of rectangular cross-section and form the peripheraledges 26', 46' of the needle discs 26, 46 respectively. A strip 39containing the needles 30 is disposed in a peripheral groove 68 of theedge 46' and fills the same. The same applies to the peripheral surface26'. The needles 30 are in each case provided in two adjacent planesperpendicular to the axis of the associated needle disc 26, 46. At theirclosest narrowest point, the peripheral surfaces 26', 46' are separatedby the space 55. Since the needles 30 are offset from one another in theaxial direction, the needles 30 on the two sides can penetrate relativeto one another without touching one another or resting on the oppositecollar 53 or 54. FIG. 3 shows the situation without the web of material.When the web of material is in the apparatus, it passes from the topneedle disc 26 to the bottom needle disc 46 when they are at theirclosest point, that is, when they are separated by the space 55. Thispoint is the transfer point 3 shown in FIG. 1. In the region of thispoint 3, the web is engaged both by the needles 30 of the top needledisc 26 and by the needles 30 of the bottom needle disc 46. The needles30 of the top needle disc 26 then lift out of the web as it continues torotate and at that moment the web has already been pinned onto theneedles 30 of the bottom needle disc 46. Thus, the transition to theneedle disc 46 occurs without any intermediate release or loosening ofthe engagement of the web 4 at its edge.

The needle discs 26, 46 and 28, 48 are peripherally coupled by the webof material and thus automatically rotate at the same peripheral speedcorresponding to the web speed. There is no need to apply a drivemechanism to the needle discs 26, 46; 28, 48 because they, like thesupport drums 29, 49, are driven by the web 4.

FIG. 4 is a side elevation showing a specific embodiment of the widthstretching unit 100. A handwheel 57 is rotatable on a spindle 47 andadjusts the supports 50 along the shaft 41 in the direction of the arrow77 (as shown in FIG. 2). Instead of the manual adjustment, a motoradjustment may be provided. At its end, the support element 56 has atransverse element 59 which is engaged by a guide 60. The guide 60 isfixed to the frame and prevents the support 50 from tipping about theshaft 41. The pivoting element 38 has a transverse element 61 at thebottom end, extending substantially parallel to and above the transverseelement 59 and being pivotable thereon about the pivot axis 15. Atransverse element 62 is also provided at the top end of the pivotingelement 36. The selvedge straightener 5, biasing brush roller 6, andsensor 12 are disposed on the transverse element 62 as shown in detailin FIG. 5.

FIG. 6 is a perspective view from the side opposite that shown in FIG.4. The reference numerals are the same. As shown, the bottom transverseelement 61 of the pivoting element 38 has downwardly extending bearingflanges 63. The bearing flanges 63 may pivot on the pivot axis 15, whichextends in the region of the transverse element 59 of the supportelement 58.

FIGS. 7 to 9 show a re-needling unit having the general reference 90. Are-needling unit 90 is associated with each web selvedge 4'. Only thedevice 90 associated with the front selvedge according to FIG. 1 andwith the left-hand selvedge according to FIG. 2 will be described. There-needling unit 90 is disposed on a support 91 rigidly connected to thesupport element 56 and with the movements of which it thus participatesin the transverse direction of the fabric direction.

A pivot axis 92 parallel to the axis of the needle disc 46 is providedon the support 91. A bell-crank lever 93 is mounted pivotally on thepivot-axis 92. A downwardly extending arm 93' is loaded in the clockwisedirection with reference to FIG. 7 by, for example, a spring 94 which isadjustable by screw 95.

Considered in the direction of rotation of the needle disc 46, the pivotaxis 92 is disposed closely above the needle disc 46 at a distance fromthe central plane M that joins the axes of the needle discs 26, 46. Thesecond arm 93" of the bell-crank lever 93 points towards the gap betweenthe needle discs 26, 46. At its free end, the second arm 93" carries aroller 96 which is freely rotatable about an axis parallel to the axisof the needle disc 46 and of the second needle disc unit 40. The roller96 rolls on the edge 46' of the needle disc 46, the roller 96 beingpressed on the edge 46' by the action of the spring 94. The needle strip39 containing the radially projecting needles disposed in two planesperpendicular to the axis of the needle disc 46 is recessed into theedge 46'. The roller 96 is substantially cylindrical in the region ofthe width of the edge 46' and has two peripheral grooves 97 in theregion of the needles 30. The grooves completely accommodate the needles30 in the manner shown in FIG. 9. The action of the spring 94 pressesthe roller 96 onto the edge 46'. The selvedge 4' of the web 4therebetween is pressed onto the needles 30 and is thus reliably pinned.In its cylindrical part, the roller 96 has a relatively small diameterof about 60 mm and is peripherally disposed as closely as possible tothe gap between the needle discs 26, 46 so that the distance betweencomplete pinning and the transfer point 3 is as small as possible.

At its axial outer end, the roller 96 has a peripheral collar 98 with aside surface 98' perpendicular to the axis of the roller 96. Roller 96is axially slidable on its shaft 99 and is pressed by the side surface98' of the collar 98 against the outer end face 46" of the edge 46' ofthe needle disc 46 by a helical compression spring 70 surrounding theshaft 99. The correct mutual position of the needles 30 and peripheralgrooves 97 is thus ensured.

FIG. 10 shows a deflecting roller 72 disposed in the region of the entryof the web 4 to the first needle disc unit 20 and adapted to avoid thefree path of the web 4 visible in FIG. 1 and denoted by reference 4" inFIG. 10. Up to the top apex of the last guide roller 8", the web ofmaterial runs in a fixed or substantially fixed guide system. To avoidthe free zone 4", a deflecting roller 72 is mounted on links 73 forpivoting about an axis 74 that is disposed in the region of the top halfof the last guide roller 8". The deflecting roller 72 may be pivoted bya linear drive 75, which engages the link 73, for example, from thebroken-line position above the zone 4" to the solid-line position. Inthe solid-line position, the web 4 wraps around the bottom part of thedeflecting roller 72 which bears against both the last guide roller 8"and against the first needle disc unit 20 or its support drum 29(between the needles 30). In this way, the fixed guidance of thematerial is ensured over the section between the last guide roller 8"and the first needle disc unit 20.

The mounting of the deflecting roller 72 at the end of the link 73 issubstantially resilient so that the deflecting roller 72 may seek acorrect position of uniform abutment against both the guide roller 8"and the support drum 29. This is shown diagrammatically by the forkedconstruction 76 at the end of the links 73 in FIG. 10.

In the embodiment illustrated, the deflecting roller 72 and the lastguide roller 8" have substantially the same diameter, while the supportdrum 29 has approximately three times that diameter.

At the needle disengagement point 14, at which point the web of material4 extends substantially vertically upwards, according to the exampleillustrated, a special needle disengaging or de-needling roller 78 isprovided to ensure that the web is satisfactorily disengaged from theneedles of the second unit 40. The de-needling roller 78 is on thebottom right in FIG. 10 and is mounted for free movement in a verticalguide 65. After being detached from the needles 30 of the second needledisc unit 40, the web of material 4 wraps round the top half of thede-needling roller 78 and then passes to a follower roller 79 in a fixedguidance system. The de-needling roller 78 bears from above against thefollower roller 79. The de-needling roller 78 is mounted to be freelymovable in the guide 65 in the direction of the arrows 66 and seeks itsposition in the vertical direction by its own weight and thelongitudinal tension in the web of material. To be able to optimize theposition of the de-needling roller 78 on contact with the followerroller 79 relative to the needles 30 of the second needle disc unit 40for the de-needling operation, the guide 65 can be adjusted horizontallyin the direction of arrow 67. This adjustment, however, is self-locking,i.e., the de-needling roller 78 cannot freely shift horizontally.

In the exemplified embodiment illustrated, the de-needling point 14 issituated somewhat above the axis of the second needle disc unit 40. Thede-needling roller 78 has a diameter corresponding substantially to thediameter of the rollers 8" and 72. The de-needling roller 78 is sopositioned by suitable displacement of the guide 65 in the direction ofarrow 67 so that the de-needling roller 78 is just out of touch with theneedles 30 of the second needle disc unit 40.

FIG. 11 shows a possibility for automating the operation of the widthstretching unit 100. An open-loop and closed-loop control system 80 isprovided. The pivoting drives 13 of the first needle disc unitexperience the transverse tensile stress of the web of material. Theyengage the respective arms 56', 58' of the support elements 56, 58 viaforce measuring elements 81, the signals of which are fed via lines 82to the open-loop and closed-loop control system 80. The width adjustmentof the second needle disc unit 40 and hence also of the first needledisc unit 20 is effected by a motor 85, which is controlled by thecontrol system 80 via a line 86. To detect the actual value of the widthadjustment of the second needle disc unit 40, a measuring device 83 canbe provided whose signal can be sent to the control system 80 via a line84.

The control can be such that the transverse tension is set to a specificvalue between a minimum and a maximum, which is governed by thetransverse tearing strength of the web and has been ascertainedexperimentally beforehand. A web of material treated in this waytherefore always has the same transverse tension and has experienced theaccompanying structural change.

Alternatively, the control system 80 may be such that a specificrequired web width is preset. This width is maintained independently ofthe tension required for the purpose. If, however, the minimum value or,in particular, the maximum value of the transverse tension is exceeded,a corresponding signal is transmitted or the unit switched off.

It is claimed:
 1. A width stretching unit for a web of material, thewidth stretching unit comprising:a first needle disc unit having firstand second needle discs disposed along a first axis at an axial distancecorresponding to a width of the web of material, the first and secondneedle discs having a multiplicity of peripherally distributed needlespointing radially outward, the multiplicity of needles intended forinsertion into selvedges of the web of material; a pivoting mechanismfor pivoting a first rotational axis and a second rotational axis of thefirst and second needle discs, respectively; a pinning mechanism forpinning the web of material by its edges onto the multiplicity ofneedles of the first and second needle discs in a region of reducedaxial distance between edges of the first and second needle discs; asecond needle disc unit associated with the first needle disc unit, thesecond needle disc unit having a second axis parallel to the first axis,the second needle disc unit further having third and fourth needle discsrotatably mounted substantially perpendicular to the second axis, thethird and fourth needle discs rotating about the second axis at the sameperipheral speed as the first and second needle discs, an axial distancebetween the third and fourth needle discs being equal to the axialdistance between the first and second needle discs in a zone ofincreased distance between the first and second needle discs; whereinthe edge of the first needle disc practically touches the edge of thethird needle disc in the zone of increased distance, and the edge of thesecond needle disc practically touches the edge of the fourth needledisc in the zone of increased distance so that it is possible for theweb of material to be transferred from the first and second needle discsto the third and fourth needle discs, respectively, withoutrelinquishing the pinning on at least one of the first or third needlediscs and at least one of the second or fourth needle discs.
 2. A widthstretching unit according to claim 1, wherein the first and third needlediscs are jointly adjustable in the direction of the width of the webrelative to the second and fourth needle discs.
 3. A width stretchingunit according to claim 2, wherein the first and third needle discs havea first common support and the second and fourth needle discs have asecond common support, the first and second common supports beingadjustable relative to one another on the second axis.
 4. A widthstretching unit according to claim 3, wherein the first and secondcommon supports each comprise a first support element having a fixedangle relative to the second axis, a second support element for thefirst and second rotational axes of the first and second needle discs,respectively, the second support element being pivotable on the firstsupport element by a pivoting drive about a pivot axis, the pivot axisbeing in a plane substantially perpendicular to the second axis,extending perpendicularly to a plane joining the first axis and thesecond axis, and being tangential to the first and third needle discsand to the second and fourth needle discs, respectively.
 5. A widthstretching unit according to claim 4, wherein the first support elementhas a radial arm substantially radial to the second axis and anaxis-parallel arm substantially parallel to the second axis, the radialarm having a foot, wherein the first support element is bent and isfixed by the foot of the radial arm on a hub mounted on the second axis,and the axis-parallel arm carries the pivot axis at its free end.
 6. Awidth stretching unit according to claim 5, wherein the first supportelement has a T-shaped construction in the plane perpendicular to theplane joining the first axis and the second axis, a web being one arm ofthe T-shaped construction and a cross-bar substantially parallel to thefirst and second axis being another arm of the T-shaped construction,the cross-bar carrying the pivot axis at an inner free end and carryinga first point of engagement of the pivoting drive at an outer free end.7. A width stretching unit according to claim 4, wherein the secondsupport element has a first end pivotably mounted on the first supportelement so as to pivot about the pivot axis, and has a second end onwhich, respectively, the first and second rotational axes of the firstand second needle discs are disposed.
 8. A width stretching unitaccording claim 4, wherein the pivoting drive is a linear drive which,as considered in the axial direction of the first needle disc unit, isdisposed axially outside the second support element, and engages asecond point of engagement near a free end of the second supportelement.
 9. A width stretching unit according to claim 1 furthercomprising at least one support drum for the web of material, the atleast one support drum disposed between the first and second needlediscs or between the third and fourth needle discs, the at least onesupport drum practically filling the gap axially between the first andsecond needle discs or between the third and fourth needle discs, andhaving approximately the same diameter as the first and second needlediscs or the third and fourth needle discs.
 10. A width stretching unitaccording to claim 9, wherein a length of the at least one support drumis adjustable.
 11. A width stretching unit according to claim 10 whereinthe at least one support drum consists of coaxial cylindrical first andsecond parts having approximately the same diameter, a periphery of thefirst and second parts being formed by freely projecting finger-likesegments, the segments having free corresponding gaps therebetween inthe peripheral direction of a width of the segments, the segments of thefirst part engaging gaps of the second part, the first and second partsbeing axially displacable relative to each other.
 12. A width stretchingunit according to claim 1 wherein the first needle disc unit is disposedabove the second needle disc unit and the web of material is guided soas to run onto the first needle disc unit substantially horizontally inthe region of a top apex line of the first needle disc unit.
 13. A widthstretching unit according to claim 12, further comprising an operator'sstation extending across the web of material above the web of materialon a downstream side of the second needle disc unit.
 14. A widthstretching unit according to claim 1 further comprising an applicationsystem for applying a treatment liquid to the web of material, theapplication system disposed in zones of the second needle disc unitaround which the web of material is wrapped.
 15. A width stretching unitaccording to claim 1 further comprising selvedge straighteners disposedat both edges of the web of material just before the entry of the web ofmaterial onto the first needle disc unit.
 16. A width stretching unitaccording to claim 1 further comprising a re-needling system disposed ateach selvedge of the web of material after a point of transfer of theweb of material from the first needle disc unit to the second needledisc unit as considered in the direction of travel of the web ofmaterial, the re-needling system exerting a pressure radially fromoutside onto the selvedge of the web of material to promote penetrationof the multiplicity of needles of the second needle disc unit into theselvedge of the web of material.
 17. A width stretching unit accordingto claim 16, wherein the re-needling system at each selvedge of the webof material comprises a roller pressed resiliently from outside onto theselvedge of the web of material or onto the peripheral edge of the thirdor fourth needle disc, the roller being rotatable about an axis parallelto the second axis of the second needle disc unit and having at leastone peripheral groove for the passage of the multiplicity of needles.18. A width stretching unit according to claim 17, wherein the roller ismounted on the first support element.
 19. A width stretching unitaccording to claim 17 wherein the roller at each selvedge has a radiallyprotecting collar by which the roller may be pressed resiliently axiallyfrom outside against an end face of the peripheral edge of the third orfourth needle disc, respectively.
 20. A width stretching unit accordingto claim 12, further comprising a last guide roller and a deflectingroller, the last guide roller disposed with its top apex situatedapproximately at the same height as the top apex of the first needledisc unit and before the web of material runs onto the first needle discunit, the last guide roller being followed by the deflecting rollerdisposed on links that pivot about a link axis situated approximately atthe height of the top half of the guide roller, a diameter of thedeflecting roller being larger than a clearance between the guide rollerand the first needle disc unit, the deflecting roller being pivotablefrom a top position above the web of material extending from the apex ofthe guide roller to the apex of the first needle disc unit to a bottomposition in which the deflecting roller contacts both the guide rollerand the support drum of the first needle disc unit between themultiplicity of needles on each edge of the first needle disc unit andthe deflecting roller being partially wrapped in its bottom zone by theweb of material.
 21. A width stretching unit according to claim 20,wherein a rotational axis of the deflecting roller is slightly shiftableat the links.
 22. A width stretching unit according to claim 12, furthercomprising a de-needling roller disposed at an outlet of the web ofmaterial from the second needle disc unit, a diameter of the de-needlingroller being larger than a clearance between the second needle disc unitand a follower roller disposed downstream of the de-needling roller, thede-needling roller being vertically guided for free movement on avertical guide in such manner that the de-needling roller rests on thefollower roller and just beyond the touch of the multiplicity of needlesof the second needle disc unit.
 23. A width stretching unit according toclaim 22, wherein the vertical guide is adjustable in the horizontaldirection.
 24. A width stretching unit according to claim 4 wherein thepivoting drives are connected to the first support elements via forcesensors that produce signals, the signals being input to a controlsystem which controls a drive motor, the drive motor controlling thewidth adjustment of the second needle disc unit.
 25. A width stretchingunit according to claim 24, further comprising a measuring device formeasuring the actual value of the set width of the second needle discunit, a signal of the measuring device being input to the controlsystem.
 26. A width stretching unit according to claim 24 wherein thecontrol system controls the width adjustment of the second needle discunit so that a transverse tension in the web of material remains betweena minimum and a maximum value.
 27. A width stretching unit according toclaim 26 wherein, in the event of a sudden drop in the transversetension in the web of material in a case of the web selvedges tearing ordisengaging from the needles, uncontrolled width-wise movement of thesecond needle disc unit is prevented.
 28. A width stretching unitaccording to claim 1 further comprising a longitudinal stretching zone.29. A width stretching unit according to claim 28, wherein thelongitudinal stretching zone precedes a width stretching zone.